I. Field of the Invention
The present invention relates to a cyclized rubber-type negative-working photoresist coating composition which provides high resolution.
II. Description of the Prior Art
ICs are currently being packed at higher densities to form LSIs or VLSIs. With this trend, a photoresist providing a higher resolution is required.
A positive-working photoresist is conventionally used for an integrated circuit which requires a high resolution. However, a positive-working photoresist is inferior in sensitivity, adhesion strength, and mechanical strength to a negative-working photoresist. On the other hand, even though a negative-working photoresist is superior to a positive-working photoresist in these respects, it cannot respond to a requirement of micronization beyond a certain limit. That is, when a rubber-type negative-working photoresist is exposed, is developed with an organic solvent and is thereafter rinsed, the crosslinked photoresist swells to degrade the resolution.
In view of this problem, one proposal suggests changing from a negative-working photoresist of the type most often used currently which mainly consists of xylene to one of the aliphatic hydrocarbon type having 5 to 12 carbon atoms, which swells only slightly. Another proposal is proposed to adopt dry developing which results in no swelling of the photoresist at all. However, these proposals have not yet led to actual satisfactory results.